In our daily life, a hinge structure is implemented when two elements are required to be folded relative to each other. The hinge structure available presently generally consists of a male member and a female member. The male member generally includes a pivot shaft and a connection portion while the female member includes a knuckle and a connection portion. Under the normal condition, the pivot shaft extends rotatably into the knuckle while one object is mounted on the connection portion. Another object is mounted on the connection portion of female member such that the two objects can be folded onto or unfolded away from each other about an axis of the pivot shaft.
In actual practice, a positioning device is disposed between the pivot shaft and the knuckle in order to lock the male and female members together. The most commonly know positioning devices include flexible elements, hooks, mortise and dovetail structures and groove-and-tongue engagements.
FIG. 1 shows an exploded view of a conventional hinge structure. FIG. 2 shows a cross-sectional view of the conventional hinge structure in a working condition. FIG. 3 shows a cross-sectional view of the conventional hinge structure in a locking condition. As illustrated, the conventional hinge structure 1 includes a female member 11, a male member 12 and a flexible unit 13.
The female member 11 has a knuckle 111 and a connection portion 112 extending from the knuckle 111. The connection portion 112 is formed with two connection holes 1121, 1122. The male member 12 has a pivot shaft 121 extending rotatably into the knuckle 111 and a connection portion 122 extending from the pivot shaft 121. The male member 12 further has a connection portion 122 extending from the pivot shaft 121 and formed with two connection holes 1221, 1222. The pivot shaft 121 when in cross section has an axis AO and defines a peripheral locking section 1211 and a peripheral working section 1212 adjacent to the peripheral locking section 1211. The peripheral locking section 1211 includes a straight line or the locking section 1211 extends along a straight line.
The flexible unit 13 is disposed within the knuckle 111, and has seating section 131 in the form of a recess for receiving the pivot shaft 121 and two flexible parts 132, 133 extending from the seating section 131 in such a manner to contact the knuckle 111. The seating section 131 has a width smaller than the length of the working section 1212. 1212
Referring to FIG. 2, when the peripheral working section 1212 is aligned with the seating section 131, the pivot shaft 121 possesses a torque due to said biasing action of said flexible unit 13. At this time, the conventional hinge structure 1 is disposed in the working state.
Referring to FIG. 3, in case the pivot shaft 121 is rotated within the knuckle 111 in the arrow direction (10) (i.e. about its axis AO) such that the peripheral locking section 1211 is aligned with the seating section 131, the pivot shaft 121 is locked to the knuckle 111 due interference between the width of the seating section 131 and the length of the peripheral locking section 1211. At this time, the conventional hinge structure 1 is disposed in the locking state.
As is known in the art, there always exist two turning angles C1, C2 between the peripheral locking section 1211 and a peripheral working section 1212 and another two turning angles C3,C4 between the seating section 131 and two flexible parts 132, 133.
Rotation of the pivot shaft 121 about its axis AO within the knuckle 111 results in severe wear whenever the turning angle C1,C2 of the pivot shaft 121 collides against the turning angle C3,C4 of the flexible unit 13, thereby preventing smooth rotation of the pivot shaft 121 in the knuckle 111 and consequently shortening the service life of the conventional hinge structure 1.